People on both sides of the political and social spectrums are angry and scared, a bad combination.
It seems some people believe "I am always right and you are always wrong" and have no respect or consideration for the possibility that perhaps there is a middle ground. In addition, they want to force their ideas onto others. You must live MY way because your way is wrong and you will be punished if you do not.
I do not know about the shooter in this instance. However, may I state that I have guns. I do not need to worry about a human intruder where I live. I do have to be vigilant about predator wildlife: bears, bobcats, mountain lions on my property. There was a bear sighting three days ago IN MY BACKYARD. When I go out now, I carry a gun. I would use it as a last resort, first yelling, waving my arms, etc., to chase it away. Shooting it would be a last resort. So please consider that not everybody who owns a gun does so to kill other people.